Helminth Fauna of the Dry Tortugas. 169 
be segmenting. A few of the early segmentation stages are shown in fig. 8. 
A few measurements, in millimeters, were made on the living worm with 
the following results: Length 178; diameter of head 4.5; greatest breadth 
of body 5, about the middle; last segment, length 2.5, breadth 2.25, with 
ripe ova, which were 0.035 and 0.032 in the two principal diameters. 
8. Anthocephalum gracile Linton. 
Report U. S. F. C., 1887, pp. 794-796, plate vi, figs. 1-2. Bull. U. S. F. C., 1899, 
pp. 275-411. Bull. Bureau of Fisheries, vol. xxIv, p. 347. 
Twelve specimens were found in the spiral valve of the sting-ray (Dasy- 
atis say), July Io. 
The following measurements, in millimeters, were taken from a speci- 
men mounted in balsam: Length 6; diameter of head 0.040; breadth of 
body just behind head 0.11; last segment, length 1.49, breadth 0.11. Stro- 
bile linear. 
g. Undetermined Cestode. 
€Plate x7 figs. 5,"6;°7.) 
One immature strobile from the spiral valve of the cub-shark (Carcha- 
rhinus platydon), July 12, probably belongs to a new genus. It was nearly 
dark when this specimen was collected, and it was not in good enough con- 
dition to risk keeping it in sea-water over night. The appearance of the 
living worm was that of having a lappet at the posterior end of each both- 
rium. In the preserved and mounted specimen this proves to be a loculus 
produced by a transverse costa near the posterior end of the bothrium. Each 
bothrium is also provided with a single auxiliary acetabulum at the anterior 
end. There are no hooks on the bothria. So far as I know, there is no 
genus of cestodes in which the bothria are without hooks and at the same 
time possess auxiliary acetabula and costa. 
The strobile is filiform, with ten segments, all of which are singularly 
long and slender. The neck is also long and slender, and both neck and 
segments are finely serrate. The reproductive apertures are marginal and 
are situated at about the posterior third. The last segment is attenuate at 
the posterior end. 
Dimensions, in millimeters, of the living worm: Length 15; breadth 
of head (variable) 0.4; bothrium (variable), length 0.29, breadth 0.19; 
distance to first segment 5.8; first segment, length 0.35, breadth 0.12; last 
segment, length 1.40, breadth 0.15. In balsam the diameter of the head 
is 0.40, while that of the neck near the head is 0.08. 
PEDIBOTHRIUM' gen. nov. 
Body tenuiform, articulate, head separated from the body by a distinct 
neck, and provided with four distinct, cruciform, armed bothria, without 
auxiliary suckers, coste or loculi. 
1 redios = even, 7%. e., without costa. 
